a. Technical Field
The present invention relates to balustrades for people moving devices in general, and to apparatus for assembling balustrades for passenger conveying devices in particular.
b. Background Art
Escalators, moving walkways, and other people moving devices efficiently move a large volume of pedestrian traffic from one point to another. Passengers step on moving steps (or belts, or pallets) and are transported along at a constant rate of speed. For safety reasons passenger handrails are provided, traveling in the same direction and speed as the steps. A balustrade assembly supports and guides one of the handrails on each side of the steps.
Each balustrade assembly includes balustrade panels (typically glass) which extend up from a base to support the handrail. The balustrade panels are supported and positioned by panel holders enclosed within the base by enclosure panels. Typically, the panel holders are attached to the frame of the device by adjustable brackets.
Proper alignment of the balustrade components is critical during assembly. Aesthetically, it is important that each balustrade be aligned with the device's other balustrade. In applications where escalators are installed side by side, it is also important that the balustrades of one escalator be aligned with the balustrades of the adjacent escalator. For safety reasons, alignment is critical to prevent injuries to passengers passing by misaligned joints.
It is known in the art that balustrades may be assembled piece by piece on the frame trusses of the escalator. Specifically, the assembly begins by locating and attaching the panel holders relative to the frame trusses. The remaining components are then located and attached to the panel holders and to each other as the balustrade assemblies are erected. There are several disadvantages to this piecemeal method of assembly.
First, mounting the balustrade components on the truss one at a time accumulates the dimensional tolerances of the components, since each piece is positioned relative to the last piece. Accumulated tolerances may not be a problem for a particular balustrade, but they are often a problem when one balustrade must be aligned with the other balustrade of that particular escalator. Moreover, alignment problems are often exacerbated when the balustrades of adjacent escalators must be aligned relative to one another.
Second, accumulated dimensional tolerances often require that one or more balustrade components be dimensionally altered before the component(s) can be installed. A person of skill in the art will recognize that the practice of custom fabricating or altering parts during assembly is a costly process. Moreover, if these parts require replacement in the future, the replacement part must also be customized.
Third, assembling each balustrade on top of the frame is cumbersome. Often scrap and debris generated during the assembly process must be cleaned out of the hardware already attached to the frame.
Fourth, it is impractical to assemble the balustrade piecemeal on the frame at the same time the rest of the escalator is being assembled. As a result, the time required to assemble the entire escalator is greater and therefore increases the leadtime of producing an escalator. A person of ordinary skill in the art will recognize that it is a competitive advantage to minimize the time required to manufacture an escalator.